1. Field of the Invention
The present invention relates to noncontact-type magnetic detection devices equipped with magnetoresistance effect elements, and particularly, to a magnetic detection device that can perform dipole detection with a simple structure, and to an electronic apparatus equipped with such a magnetic detection device so as to allow for a simple switching operation between predetermined modes.
2. Description of the Related Art
Normally, when a notebook personal computer is closed with the power left on, the computer switches to a sleep mode, which is a power-saving mode where the display screen is turned off.
On the other hand, a switching operation with the use of software for maintaining the normal operation mode even when the notebook personal computer is in a closed state has been implemented in the related art. In this case, for example, the display screen is kept turned on without being switched to a sleep mode even while the notebook personal computer is in a closed state. See Japanese Unexamined Patent Application Publication Nos. 11-85449, 9-274474, 2006-163294, and 2004-310658 for examples of related art.
However, to perform such a switching operation through the use of software as described above, it is necessary for the operator to first perform a preliminarily input operation on the computer while kept in an opened state so that the computer can be set to a non-sleep mode when it is closed. Furthermore, in the case where the setting and cancelling of a non-sleep mode are to be performed through the use of software as mentioned above, a corresponding program must be activated every time to perform the setting or cancelling operation. This unfavorably places an excessive burden on the operator.
None of the inventions set forth in Japanese Unexamined Patent Application Publications mentioned above includes any description with regard to the setting and cancelling of a non-sleep mode for the closed state of a notebook personal computer.
Japanese Unexamined Patent Application Publication No. 11-85449 discloses an invention that relates to a process for detecting the opening and closing of a notebook personal computer through the use of software.
Although Japanese Unexamined Patent Application Publication No. 9-274474 discloses an invention that relates to a slide switch, a detection circuit thereof is undesirable due to its complex configuration. In addition, since this slide switch is of a contact type, the slide switch is problematic in that it cannot ensure a long life span.
Japanese Unexamined Patent Application Publication No. 2006-163294 discloses an invention that relates to detection of the orientation of a portable phone by means of an acceleration sensor. Therefore, it is unlikely that this can be applied to the setting and cancelling of a non-sleep mode.
Japanese Unexamined Patent Application Publication No. 2004-310658 discloses an invention for detecting the rotation of a display portion of a notebook personal computer by using a magnetic detector element and a magnet. It is mentioned in Japanese Unexamined Patent Application Publication No. 2004-310658 that the magnetic detector element is defined by a reed switch. However, since a reed switch is a proximity switch, it is necessary that the magnet be distant from the reed switch in order to create a non-magnetic-field condition where an external magnetic field is not effective on the reed switch. In addition, a rotation-detection method that employs a reed switch always requires at least two reed switches at positions distant from each other. Specifically, it is necessary that when one reed switch is detecting a magnetic field, the other reed switch be placed at a position where it does not detect the magnetic field, and vice versa. This disadvantageously tends to increase the size of the device.